The economy all over the world today is built on the basis of fossil fuel, such as coal, oil and natural gas. However, all of these non-reproducible fossil energies are continuously exhausted. Since the beginning of the 21st century, the global energy problems and the consequent problems of environmental pollution and climate warming are becoming more and more prominent and gradually intensified. Because of the outstanding advantages of wide and broad distribution, large scale resources, pollution-free, clean, safe, and easy to obtain, the solar energy is considered to be one of the most promising renewable energy. The solar cell converts the solar energy to electric energy directly, thus it is a practicable method for utilizing the solar energy. However, currently commercial solar cells are all limited to the silicon-based inorganic solar cell, but the cost is so high that people cannot accept it, thus the scope of their use is significantly limited. For a long time, to reduce the cost of the solar cell and expand the range of application, people have been looking for new type of solar cell materials.
The organic solar cell is a new type of solar cell. Compared to the disadvantages of limited source, expensive price, toxic, complicated manufacturing process and high cost of the inorganic semiconductor material, the organic solar cell has the incomparable advantages that the inorganic solar cell doesn't have, such as wide sources of raw materials, a variety of structures and good adjustability, low cost, safety and environmental protection, simple manufacturing process, light weight, possibly to produce in a large flexibly area, and the like, it can be widely used in construction, lighting and power generation and other areas, thus it has an important development and application prospects. Therefore, many domestic and foreign research institutes and enterprises are paying considerable attention and investment to the field of organic solar cell. However, until now, the photoelectric conversion efficiency of the organic solar cell is much lower than that of inorganic solar cell. Therefore, the development of new organic photovoltaic materials has much importance for improving the efficiency of organic solar cells and other semiconductor devices.